MONOLITHIC GAAS HBT P-I-N-DIODE VARIABLE GAIN AMPLIFIERS, ATTENUATORS, AND SWITCHES

We report on monolithic circuits integrating HBT's and p-i-n diodes us ing a common HBT MBE structure. An HBT variable gain amplifier using a p-i-n diode as a variable resistor achieved a gain of 14.6 dB, a band width out to 9 GHz, a gain control range of > 15 dB, and an IP3 of 28 dBm. A two-stage HBT p-i-n diode attenuator from 1-10 GHz and an X-ban d one-pole two-throw HBT p-i-n diode switch were also demonstrated. Th e two-stage p-i-n attenuator has over 50 dB dynamic range at 2 GHz and a maximum IP3 of 9 dBm. The minimum insertion loss is 1.7 dB per stag e and has a flat response to 10 GHz. The X-band switch has an insertio n loss of 0.82 dB and an off -isolation of 25 dB. The bandwidth is gre ater than 35% and the IP3 is greater than 34.5 dBm. These circuits con sist of p-i-n diodes constructed from the base-collector MBE layers of a base-line HBT process. This work demonstrates the first monolithic integration of p-i-n diode switch, variable gain control, and attenuat ion functions in an HBT technology without additional processing steps or MBE material growth.